DESCRIPTION: The increasing use of A/M and the consequences of its use continue to generate social and governmental concern, which has been manifested in increased public attention and initiatives to improve interdiction, prevention, and treatment strategies, with a priority placed on research efforts to inform these strategies. The proposed continuation will conduct further research on a diverse sample of treated and untreated A/M users to provide an empirical basis for the improvement of prevention and treatment strategies now being developed. The continuation will extend the research by administering a follow-up Natural History Interview (NIH) to the current study's sample of 400 randomly sampled individuals admitted to treatment for A/M use in 1995-97 to publicly funded outpatient and residential programs in Los Angeles County. The continuation will expand the research to interview (using the same NHI) a sample of users who have never been in treatment in order to better understand the untreated course of A/M use and barriers to treatment entry. Two broad primary aims will be addressed: (1) Assess AIM use patterns over time and determine the long-term consequences of A/M use, including the conditional impact of demographic, background, and health characteristics, and the relationships of A/M use histories to other substance use, HIV/AIDS risk behaviors, and criminal behaviors. A/M use histories and related characteristics will be compared between the treated and untreated groups. (2) Examine long-term treatment outcomes (including differential effects for ethnicity, gender, modality, and other user characteristics) and patterns of treatment utilization for A/M users. Motivation, addiction severity, and other barriers limiting treatment access for the never-treated sample will also be described. Multivariate analyses including generalized models for repeated measures, survival analysis, logistic regression, structural equation modeling, and growth modeling, as well as ethnographic methods, will be used to address these aims. New data from the proposed continuation will allow analysis of longer A/M use histories and assessment of long-term treatment outcomes (not yet studied for AIM users). Findings will serve to improve strategies for treatment outreach, engagement, service delivery, and retention, and to design risk reduction programs exterior to the treatment system.